A cheshbon hanefesh is an essential component of doing teshuvah.
Furthermore, there is sur me'ra (turn from evil) aspect of cheshbon hanefesh and also an aseh tov (do good) aspect.
I'm very into investing in the aseh tov aspect because that automatically brings one to turn from evil.
Not always, but a lot of times it works out like that.
For example, many people struggle with appropriate reading material for Shabbos.
This is really common, particularly during long Shabbos and particularly for people who are new to the whole thing and struggle to occupy themselves in way that is permitted according to the Laws of Shabbat, (i.e. no phones, no electronic entertainment or diversions, etc.).
That's all normal.
What happened for me was the more I read kosher things, Shabbat Laws and inspiration, and the more I emotionally bonded with Shabbat, the more I felt the negative effect of non-Shabbosy reading material.
It took me out of Shabbat in a tangibly unpleasant way.
In other words, reading non-Shabbosy material became too uncomfortable to continue doing it.
(For the details, please see that previous post.)
So when we work on ourselves, we naturally start to feel an aversion to non-Torah behaviors & activities.
It may take time, but it happens as long we keep going.
A Time to "Just Do It" & A Time for Gradual Influence
For example, rather than continuously reading up on the deeper meanings of Shabbat, one should simply start keeping it.
Yes, keep reading about it!
But Shabbat is one of these things that the act of doing it brings connection in its wake.
Likewise, I heard that men new to Judaism should simply start learning Gemara.
Yes, it must be introduced on a level manageable for a newbie, but anecdote after anecdote has proven the value of just sitting a Jewish guy down and learning with him.
And placing oneself in the influence of Torah affects one all on its own.
For example, after I spent a year in Eretz Yisrael, I entered one of the Orthodox shuls I'd attended before that year, and was happily shocked to notice that 5 or 6 women were now wearing shaitels.
Before, they either weren't covering their hair at all or they covered the top of their head with a hat and wore the rest of their hair loose or in a ponytail.
Interestingly, these women were mostly not baalot teshuvah, but had been attending shul in this modern Orthodox community since they were little.
That year, the community imported a kollel.
Now more frequent and steady Torah-learning occurred, plus the variety and amount of Torah classes blossomed.
Of course, the shul rabbi had always given shiurim, both to men and women.
But this injection of copious Torah affected the community more in 1 year than the rabbi had in 2 decades.
And for what it's worth, I also believe in the power of the support of Torah.
When a community decides to support Torah learning, even if they themselves aren't on that level, it grants them favor from Heaven.
It increases their merits.
Plus one mitzvah leads to another in its wake.
So the effect of increasing a Torah influence in the community rendered an unanticipated & powerfully positive effect.
Real Change Comes When Wrong becomes More Uncomfortable than Right
For example, I tend to take a strong stand against shaitels that clearly violate halacha by all major opinions (including the opinions of those who solidly permit shaitels).
I often call them "va-va-voom shaitels" or "Las Vegas showgirl shaitels."
And yes, I think there does need to be at least some pushback against this trend.
They need to be called what they actually are: Not pretty. Not nice.
(I could use stronger language than that based on Chazal, but let's just stick with the above.)
Many people really do not know that these shaitels are halachically problematic.
(Well, that's not completely true. The men know because they know how seeing such shaitels, especially combined with the makeup and heels, makes them feel. But many women really don't know. They think it's chumros and anyway, when everyone else is doing it, it honestly doesn't seem so bad.)
At the same time, I know full well that real change won't occur unless a mental & heart change occurs.
Unless a woman feels that undignified behavior or dress is too uncomfortable to bear any longer, she won't really change.
And by "uncomfortable," I mean emotionally uncomfortable.
And this is true for anybody.
Change Others by Example, Not by Rebuke
If one suffers from "evil" in one's heart (even if one is otherwise a good person, but hey, no one is perfect except Hashem), then one simply accept reproof; the heart rejects it.
There is only one way, says Rav Dessler: "...show him the perfection and unity of the spiritual life."
Meaning, the beautiful interaction of a genuinely frum family, the multi-faceted relationship of a real rav and his talmidim in a good yeshivah, and other such examples.
Rav Dessler reassures us that even one with evil in his heart will still see the truth in other people (who behave correctly), and this eventually brings one to see what is wrong in his or her own heart, and thus correct it.